A power distribution system is the downstream terminal of a power supply system and is closely related to the end users of electrical power. For general residences or office buildings, the setup of power distribution system is complicated and mistakes often occurs in the setup operation, which leads to re-doing of the setup operation and additional working hours are wasted. Since the working hours spent in setting up a power distribution system is directly related to the installation cost, the overall cost of setting up a power distribution system cannot be lowered if the operation complication for setting up the power distribution system cannot be simplified and the rate of incorrect setup be reduced. Further, a conventional power distribution system is often set up according to the preference of a user and once modification of power supply is to be done, a great expense of re-installing the system is needed. Apparently, the existing power distribution system provides almost no flexibility in modifying the system arrangement. Further, a constructor of an existing power distribution system must predict all potential problems in setting up the power distribution system in order to eliminate the potential risk of re-installing the system. Thus, it is desired to improve the conventional power distribution systems.